Frictional spring.



. B. S.'JOHNSON.

FRICTIONAL SPRING.

APPLICATION FILED OCT. 18. 19 15.

Patented Dec. 18, 1917;

2 SHEETS-SHEEI 1.

T A TTORNEY lllll .1 Q

WITNESS:

B. S. JOHNSON.

FRIKCTIONAL SPRING.

APPLICA'HON FILED OCT. 18 I9l5.

Patented Dec. 18,1917.

2 SHEETSSHEET 2- II Il f I 7 II '5 If f 22 \v I Z] I INVENTOR. W I! I9 fi'md' 6 0/1 BY 1 U T TTORNEY UNITED sTA'r s PATENT oFFIoE.

BRADLEY S. JOHNSON, OF CHICAGO, ILLINOIS, ASSIGNOR TO WILLIAM H. MINER, OF

' CHAZY, NEW YORK.

FRICTIONAL srnme.

Specification of Letters Patent. Patented Dec, 1917.

Application med October 18,1915. Serial No. 56,410.

To all whom it may concern:

Be it known that I, BRADLEY S. JOHNSON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvementin Frictional Springs, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

This invention relates to improvements in frictional springs.

The object of the invention is to provide a spring adapted to absorb heavy shocks and so constructed that it not only affords the usual resistance to axial compression but creates a frictional resistance due to sliding contact of adjacent coils.

Another object of the invention is to provide a spring of the type above indicated so arranged that upon longitudinal compres sion of the same, the diameter of the coils is either increased or decreased and thereby adapted to create additional friction in contact with a friction shell or cylinder, the entire arrangement being more particularly adapted for railway draft gears.

In the drawing forming a part of the specification, Figure l is a longitudinal, sectional view of a railway car draft rigging showing my improvement in connection therewith. Fig. 2 is a view similar to Fig. l but illustrating a different embodiment of my improvement. Fig. 3 is a side elevation upon an enlarged scale, of the spring/illustrated in Fig. 1. And Fig. 1 is a detail perspective of a portion of the spring illustrated'in Fig. 1.

In said drawing, and referring to Figs. 1, 3 and 4, 10 denotes a draft sill of a railway car to which is secured rear stop 11 and front stop 12. The draw-bar 13 is shown as operatively connected with the gear proper, hereinafter described, by a yoke 14 and within the yoke is mounted a rear fol lower 15, friction cylinder 16 and spring cap or follower 17 the latter being telescoped within the friction cylinder 16. The parts are or may be supported by a saddle or tie plate 18.

Within the cylinder 16 is mounted my improved spring, the same being of helical formation, the coils 19-l9 the e f b3 5 tions of one coil will be slightly angularly offset from those of the next coil. In other words, the corrugations of the coils are either slightly in advance or slightly to the rear of the corresponding corrugations of the preceding adjacent coil. By this means, portions of each coil are normally in contact with each other as indicated at 2121. As clearly illustrated in Figs. 1, 3 and 4 the points of contact 21 will always be slightly offset circumferentially of the coil to correspond with the corrugations. Between the points of contact 21, the portions of each coil are separated and thereby permit the axial spring compression. With the construction as above described, upon axial pressure applied to the spring, it is apparent that not only will the usual spring action occur to resist the pressure but on account of the corrugations being in contact with each other at the points indicated, the various coils will slide upon each other with a twisting motion thereby creating frictional resistance between the sliding c0ils.- The tendency will be for the corrugation of one coil to aline itself with the corrugation of the next adjacent coil and if the arrangement of the points of contact 21 is as illustrated in Figs. 1, 3 and 4, it is apparent that the tendency of the coil during the twisting action will be to enlarge its diameter. I therefore design the spring so that under normal conditions the outer edges 22'22 of the coils are normally in engagement with the interior cylindrical surface 23 of the shell 16. Hence, upon compression of the spring and enlargement of its diameter, as above described, friction will be created between the edges 22 and the cylindrical surface 23, which friction increases automatiordinary coil spring 24 extending from the front end of the gear to the rear end of the shell 16, in the frictlonal spring above described.

Referring now to Fig; 2, the arrangement of sills, draw-bar, stops, yoke and followers is or may be the same as that shown in Fig.

1: However, in the modified form I provide a cylindrical friction shell 25 having an exterior cylindrical friction surface 26 with which the inner edges of the coils of the helical spring B are normally in engagement. A spring cap or follower27 is em ployed, the, same being telescoped on the exterior of the friction cylinder 25, and'for additional capacity I have shown an ordinary spring 28 mounted within the spring cap 27 and cylinder 25. In this arrangement, the frictional spring B is substan-' tially the same as that illustrated in the otherfigures of the drawing except that I so arrange the points of frictional contact between the corrugations or undulations of coils that, upon. axial compression of the spring, the tendency will be for the coils to decrease their diameter and thereby gradually augment the frictional contact between which spring 24 is nested withthe inner edges of the spring coils and the exterior cylindrical friction surface 26.

I claim:

, 1. A spring adapted for use in draft gears and the like and having a plurality of coils, each of the coils being provided with a plurality of corrugations, the corrugations of one coil being slightly in advance of the corresponding corrugations in the next adjacent coil, the corrugations being so arranged that upon axial compression of the spring, sliding frictional contact between portions of corresponding corrugations in adjacent coils will occur.

2. A helical spring of the character described having each convolution thereof provided with corrugations, the corrugations extending radially of the spring, and being progressively angularly offset, the corrugations beingnested in position to thereby eflect frictional engagement between the convolutions upon axial pressure applied to the spring.

In witness that I claim the foregoing I have hereunto subscribed my namethis 6th day of October, 1915.

BRADLEY S. JOHNSON. 

